MCAT Prep Biology: The Cell

These vocabulary flashcards cover the fundamental concepts of cell biology, including cell theory, eukaryotic and prokaryotic differences, and the specific functions of cellular organelles.

Cell Theory

A theory consisting of four basic tenets: all living things are composed of cells, the cell is the basic functional unit of life, cells arise only from preexisting cells, and cells carry genetic information in the form of $DNA$ which is passed from parent to daughter cell.

Eukaryotic Cells

Cells that can be unicellular or multicellular and contain a true nucleus enclosed in a membrane, along with other membrane-bound organelles.

Prokaryotic Cells

Always single-celled organisms that do not contain a nucleus; their genetic material is found freely floating in the cytoplasm.

Cytosol

A semi-fluid substance that facilitates the movement and diffusion of molecules throughout the cell.

Nucleus

The control center of the cell and repository for genetic information encoded in $DNA$ which is organized into chromosomes.

Nucleolus

A subsection of the nucleus that is not involved in storing $DNA$ but is responsible for producing ribosomal RNA ($\text{rRNA}$).

Nuclear Envelope

Also known as the nuclear membrane; it is a barrier that surrounds the nucleus and separates it from the cytoplasm.

Nuclear Pores

Passageways in the nuclear envelope that allow for selective two-way exchange of material between the cytoplasm and the nucleus.

Genes

The coding regions found within the genetic material ($DNA$).

Mitochondria

The powerhouses of the cell responsible for generating energy in the form of $ATP$ using the tricarboxylic acid cycle ($\text{Krebs cycle}$) and the electron transport chain.

Cristae

Numerous infoldings of the inner mitochondrial membrane that increase the surface area available for energy-producing reactions.

Mitochondrial Matrix

The internal compartment of the mitochondrion containing enzymes of the $\text{Krebs cycle}$, as well as mitochondrial $DNA$ and ribosomes.

Extranuclear Inheritance

The transmission of genetic material independent of the nucleus, characteristic of mitochondria because they contain their own genes and replicate via binary fission.

Lysosomes

Membrane-bound organelles involved in intracellular digestion and the breakdown of substrates.

Endoplasmic Reticulum ($\text{ER}$)

A series of interconnected membranes contiguous with the nuclear envelope responsible for protein and lipid synthesis.

Rough Endoplasmic Reticulum ($\text{RER}$)

A variety of $\text{ER}$ studded with ribosomes that allows for the translation of proteins destined for secretion directly into its lumen.

Smooth Endoplasmic Reticulum ($\text{SER}$)

A type of $\text{ER}$ that lacks ribosomes and is primarily utilized for lipid synthesis and detoxification.

Golgi Apparatus

Stacked membrane-bound sacs where cellular products are modified, packaged, and directed to specific cellular locations via vesicles.

Exocytosis

The process by which secretory vesicles release their contents outside of the cell.

Peroxisomes

Organelles responsible for the breakdown of fatty acids.

Cytoskeleton

The internal framework of the cell that provides structure and maintains cell shape, consisting of microfilaments, microtubules, and intermediate filaments.

Microfilaments

Solid polymerized rods of actin that provide structural protection for the cell and use $ATP$ to generate force for movement by interacting with myosin.

Microtubules

Hollow polymers of tubulin proteins that provide pathways along which motor proteins like kinesin and dynein carry vesicles.